In recent years, attention has been focused on imprint technologies for microprocessing or nanoprocessing. Imprint processes are represented by a pattern formation technique using a mold (mold member) having a micro- or nano-relief structure formed on the surface of a substrate, wherein the relief structure is transferred onto a work-material thereby achieving one-to-one transfer of the micro- or nano-structure.
A photoimprint process has been known as one of such imprint processes. According to this photoimprint process, for instance, a photocurable resin layer is formed as a work-material on an imprinting transfer substrate, and a mold (mold member) having any desired relief structure is pressed against the resin layer. In this state, the resin layer is irradiated with ultraviolet radiation from the mold side for curing, after which the mold is released off from the resin layer, whereby the relief structure that is an inversion of the relief structure that the mold has may be formed on the resin layer that is the work-material. Such a photoimprint process makes it possible to form a nanometer-order pattern that has hardly been provided with conventional photolithography, so it would offer a promising option for the next-generation lithography.
For such an imprint process, it is required to prevent the resin layer from adhering to the surface of the mold as the mold is released off from the cured resin layer. For prevention of such adherence, there have been some methods proposed, including a method in which release treatment is applied to the surface of the mold (Patent Publication 1), a method in which an adhesion layer is interleaved between the imprinting transfer substrate and the cured resin layer to improve adhesion between both (Patent Publications 2 and 3), and a method in which a photocatalytically active substance film provided on the surface of the mold is irradiated with ultraviolet radiation to improve the ability of the mold to be released off from the cured resin layer (Patent Publication 4).